The present invention relates to an automotive control apparatus and method, or more in particular an apparatus and a method for controlling the output of a power train including an engine, a transmission and driving wheels in accordance with the intention of the driver and the result of recognition of other vehicle running immediately ahead.
A conventional technique for changing the drive mode of an automotive vehicle in accordance with the conditions of other vehicle running immediately ahead or the intention of the driver of vehicle is described in Japanese Patent Application Laid-open No. JP-A-47862. This patent publication discloses a method of switching the drive mode of a vehicle in accordance with the driving condition of other vehicle running immediately ahead or in accordance with the intention of the driver of the concerned vehicle, as selectively judged by the driver of the following vehicle. In other words, the driver of the own vehicle determines one of the two drive modes by his or her own judgment so that the driver can drive his or her vehicle with the driving force as intended.
Establishment of a technique for detecting the distance between and relative speeds of one vehicle and another vehicle running immediately ahead (including an obstacle lying ahead) by use of a radar for securing the safety of the following vehicle is an urgent current problem. In the prior art described above, it is indispensable to attain the drive mode intended by the driver (the linear feeling of acceleration corresponding to the accelerator pedal stroke) and to secure the safety (collision prevention) at the same time.
In the conventional method of controlling the drive mode of a vehicle which still finds applications, however, primary emphasis is always placed on the intention of the driver. Therefore, it is technically difficult to automatically switch the drive mode of a following vehicle taking both the safety of the particular following vehicle and the driving condition of a vehicle running immediately ahead into consideration. This switching operation has hitherto been left to the manipulation of the driver of the following vehicle. As a result, if the difference is large between the calculated control parameter values of the above-mentioned two drive modes, the torque changes so abruptly that an unexpected acceleration/deceleration change occurs unavoidably against the will of the driver of his own vehicle.
In the prior art, assume, for example, that the driver who has so far maintained the accelerator pedal stroke at a low value switches to a mode corresponding to the driving condition of a vehicle running immediately ahead, i.e. a mode for chasing the vehicle running immediately ahead. A deviation occurs between a target value intended for by the driver of the vehicle and an actual target control value for the chasing operation, thereby causing an undesirable torque change uncomfortable to the driver of the vehicle.
JP-A-7-189795 and JP-A-8-304548 disclose that an engine and a transmission are controlled with the control parameter such as a driving torque at a output shaft of the transmission.
The object of the present invention is to provide an automotive control apparatus and control method, in which a control amount for securing the safety of a vehicle and a control amount for attaining a mode intended for by the driver of the vehicle can be switched while reducing the shock from the power train, thus making it possible to secure the safety and the maneuverability of the vehicle at the same time.
The present invention provides an automotive control apparatus, in which fluctuations of at least selected one of the driving torque, the driving force and the acceleration/deceleration rate are suppressed in the case where a deviation beyond a predetermined value occurs between a first target value before change of at least one of the driving torque, the driving force and the acceleration/deceleration rate and a second target value calculated in accordance with the drive mode intended for by the driver or the driving environment ahead.
According to a first preferred aspect of the invention, there is provided an automotive control apparatus for setting a target value of the driving torque on the output shaft side of the transmission based on at least the accelerator pedal stroke and controlling at least the engine toque in accordance with the target value, comprising means for setting a drive mode intended for by the driver or means for recognizing the driving environment ahead, means for changing a target value in accordance with the signal produced from one of the foregoing two means, and means for suppressing the fluctuations of the driving torque in the case where a deviation of not less than a predetermined value occurs, in switching the target values, between the first target value before change and the second target value calculated according to the above-mentioned signal.
According to a second preferred aspect of the invention, there is provided an automotive control apparatus comprising means for detecting an actual vehicle acceleration/deceleration rate and means for detecting an actual vehicle speed in addition to the accelerator pedal stroke as a signal used for calculating a target value of the driving torque.
According to a third preferred aspect of the invention, there is provided an automotive control apparatus in which the torque fluctuation suppression means causes the target value change means to change the first target value first at a predetermined progressive rate for a predetermined length of time from an initial value and switches it to a second target value when the deviation between the first and second target values is reduced to a predetermined level.
According to a third preferred aspect of the invention, there is provided an automotive control apparatus, in which the torque fluctuation suppression means causes the target value change means to switch the second target value to the first target value instantaneously.
According to a fourth preferred aspect of the invention, there is provided an automotive control apparatus, in which the signal produced by the drive mode setting means or the environment recognition means represents the headway distance and the relative speed with the vehicle running immediately ahead.
According to a fifth preferred aspect of the invention, there is provided an automotive control apparatus for setting a target value of the driving torque on the output shaft side of the transmission based on at least the accelerator pedal stroke and the actual vehicle deceleration rate and controlling at least the engine torque and the transmission ratio in accordance with the target value, comprising means for calculating a target value of the rotational speed on the input shaft side of the transmission in accordance with the target value and a target rotational speed limit setting means for setting a limit to the target rotational speed on the input shaft side of the transmission.
According to a sixth preferred aspect of the invention, there is provided an automotive control apparatus for setting a target value of the driving torque on the output shaft side of the transmission based on at least the accelerator pedal stroke and the actual vehicle deceleration rate and controlling at least the engine torque and the transmission ratio in accordance with the target value, comprising means for calculating a target value of the transmission ratio in accordance with the target value of the driving torque and target transmission ratio limit setting means for setting a limit to the transmission ratio.
According to a seventh preferred aspect of the invention, there is provided an automotive control apparatus for setting at least one of the driving torque, the driving force and the acceleration/deceleration rate on the output shaft side of the transmission as a target value based on at least the accelerator pedal stroke and controlling at least the engine torque in accordance with the target value, comprising means for calculating the driving load of the vehicle, means for calculating the actual deceleration rate of the vehicle, means for calculating a target deceleration rate based on at least the deceleration rate calculated y the deceleration rate calculation means and the accelerator pedal stroke, and means for calculating the target value in accordance with the driving load calculated by the driving load calculation means and the target deceleration rate calculated by the target deceleration rate calculation means.
According to an eighth aspect of the invention, there is provided an automotive control apparatus wherein the driving load calculation means is weight rewrite means capable of rewriting the magnitude of the driving load calculated.
These means can solve the above-mentioned problems.